Grinding machine



F. cooKE GRINDING MACHINE April 21, 1964 2 Sheets- Sheet 1 Filed Jan. 51, 1962 I INVENTOR HQANK Coo/(E 2% ATTORNEY April 21, 1964 F. COOKE 3,129,533

GRINDING MACHINE Filed Jan. 31, 1962 2 Sheets-Sheet 2 6 /Z4" Z ,30 I20 /32 3O INVENTOB. RANK Coo/ 5 A ,7- TOENEY United States Patent 3,129,533 GRINEIWG MACHINE Frank Cool-:e, North Brookfield, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Filed Jan. 31, 1962, Ser. No. 170,967 19 Claims. (ill. 511tll) The invention relates .to a grinding machine arid more particularly to a machine for grinding the internal annular contoured surface of a generally cone shaped radome on which the external surface has been prefinished. in manufacturing of ceramic radomes it is important that the radome wall be smoothly contoured and of a closely controlled predetermined transverse dimension throughout that is unattainable by molding methods, so as to minimize the adverse effect on microwave signals transmitted therethrough. The grinding apparatus disclosed herein is provided for achieving this result by precision grinding the internal wall of the radome excluding the spherically shaped nose portion which is ground thereafter by an apparatus which is the subject of my copending application Serial No. 170,089 filed January 31, 1962.

It is, therefore, the primary object of this invention to provide apparatus for precisely grinding the internal annular contoured surface of a radome. Another object of the invention is to provide apparatus that is sturdy, vibration free and rigidly supports the cutting tool. A further object of the invention is to provide grinding apparatus utilizing a grinding boom and a coacting cutting tool support movable together in a predetermined relation to a radome during a grinding operation. A still further object is to provide apparatus including portions counterbalanced to eliminate the application of substantial forces to a radome during the grinding operation and thereby prevent fracture of the frangible radome wall. A further object of the invention is to provide a gaging or sizing apparatus which contacts and utilizes the prefinished external surface of the radome as a reference during the grinding operation. A further object is to provide apparatus in which the vertical movement of the pivotal boom and the movement of the longitudinally movable table are synchronously controlled. A still further object of the invention is to provide adjustable and rotatable radome supports for aligning the longitudinal chord of the arc of the radome wall along which the grinding operation is performed on a line substantially parallel to the line of movement of the table for traversing the radome.

Generally, in its preferred form, the apparatus embodying the instant invention consists of a base portion including a pair of spaced parallel vertical slideways sup porting a synchronously movable slide on which is mounted a pair of heads. Pivotally mounted on a shaft between the heads and the slideways is a freely pivotable counterbalanced unit including a vertically movable boom and a coacting cutting tool support. The boom supports a feed mechanism on which is mounted a narrow free rolling follower or disc contacting and rolling along the circumference of the prefinished external surface of a radome. The cutting tool support supports a pneumatically driven grinding head upon which a grinding wheel is mounted to be driven thereby. The grinding wheel is mounted directly opposite the free rolling disc for rotation about an axis substantially parallel to that of the disc, with the radome wall rotating and traversing therebetween.

Slidably supported on the base and synchronously driven in timed relation with the vertical movement of the boom is a table. Upon the table a radome to be ground is rotatably driven and supported on rollers in a predetermined position, preferably so that the highest 3,129,533 Patented Apr. 21, 1964 point of the radome wall, which typically forms a shallow arc, is disposed midway of its longitudinal chord or of the total distance to be traversed, so that the vertical rise and fall of the arc is substantially the same on either side of the midpoint.

These and other features, objects and advantages of the invention will become apparent in the following description and by reference to the accompanying drawings in which,

FIG. 1 is a View in elevation of the apparatus, parts of which are broken away and sectioned for clarification of various features embodied therein,

'FIG. 2 is a View of the apparatus taken approximately on line 2- 2 of FIG. 1,

FIG. 3 is a partial vertical section illustrating an alternative embodiment of the cutting tool,

FIG. 4 is a view in elevation of details of an alternative configuration of the drive for the ventical slide, and

FIG. 5 is a schematic representation of control circuits for the reversible motor.

Referring to the drawings, the apparatus comprises a base it) 'upon which a table 12 is :slidably mounted on ways 14 and in. lntegral with or fixed to the sides of the base 1% is a pair of parallel vertically spaced supporting members 18 and 2% upon which parallel vertical slideways 22 and 24 are machined. Slidably mounted on the vertical slideways 22 and 24 is a horizontally disposed slide 26 which has a pair of spaced surfaces. engaging the slideways 22 and 24 and a horizontally adjustable slide-way 23 on which spaced heads 36* and 32 are adjustably mounted. A pair of L-shaped brackets 34 and 36, fixed-1y mounted on the heads 36 and 32 by suitable attachment bolts, in turn support fixedly mounted clamping blocks 38 and 40. These clamping blocks 38 and 49 receive and secure the opposite ends of a horizontally disposed transverse shaft 42 spanning the distance between the heads 30 and 32, so that shaft 42 is fixed against movement.

A housing 44 of a generally triangular transverse shape is pivotally mounted upon the shaft 42 between the L- shaped brackets 34 and 36 by means of spaced bearings 46 and 48 through which the shaft 42 passes. Adjustably mounted and fixed within a pair of bores near the top of the housing 44 is the supporting means for a V-shaped boom 5ft compnising a pair of parallel longitudinally adjustable shafts 52 and 54, located in said bores, having end plates 56 and 58 integral therewith. A pair of tubular members 60 and 62 forming the V-shape of the boom 50 are fixed to the plates 56 and 53. To rigidly support the boom 50 a turn buckle arrangement is provided 'including a shaft 64 pivotally attached near the remote end of the overhung boom Stl, an adjusting nut 66, and a shaft 68 pivotally connected to an upstanding bracket 70 fixed to the top of the housing 44. By rotating the nut 66 the oppositely threaded shafts 64 and 68 may be put in tension to rigidly support the boom 50 relative to the housing 44. Fixed to and supported by the boom 5%) is a cutting tool feeding mechanism 72 comprising a base 7 4 having a vertical slideway '76 on which is mounted a movable slide 78 with mating surfaces engaging the slideway 76. A nut 80 traversable within an opening in the base 74 is fixed to the slide 78 and engages a rotatable feed screw "82 journaled in the base 74. The screw 82 has a handle 84 fixed to it for manually rotating the feed screw 82 and thereby traversing the slide 78 on the base 74.

Adjustably fixed in a transverse T-slot in the slide 78 is a corresponding T-shaped head supporting a shaft 36 on which a follower is rotatably mounted. This follower comprises a bearing 88 supporting a narrow roller 0r disc 89 with "a 'convexly shaped periphery, which contacts the 3 prefinished surface of a work piece or radome R to establish a reference for the grinding operation.

Centrally mounted in, adjustably fixed to and extending through a large bore located near the bottom of the pivotally supported housing 4 is a rigid cutting tool or grinding wheel support member 91). The cutting tool support member 91 has fixed to the left hand end of its gradually tapering portion, as shown in FIG. 1, a bracket 92 to which is clamped a pneumatically driven cutting tool rotating device 94 of the sort generally available commercially. The device 94 has a cutting tool such as a grinding wheel fixedly mounted to its rotatable shaft, preferably of a small diameter and having a convex shaped peripheral cutting ourface which lies substantially in the same plane with but opposite the follower disc or roller '89. As noted above, the axis of rotation of the roller 39 and that of the cutting tool 95 are disposed substantially parallel to each other. A flexible conductor 98 for conveying air from any suitable source to drive the pneumatic device 94 is fastened to the cutting tool support 91? and is connected to the pneumatic device 94 in any well known manner.

The cutting tool of the instant invention is preferably a diamond impregnated rotatable grinding wheel that has long life and which requires little or no dressing when grinding the internal surface of a ceramic radome. However, a stationary tool may be utilized such as a diamond impregnated tool bit rigidly fixed on the support member 90 in place of the grinding wheel. This arrangement is illustrated in FIG. 3.

To prevent the fragile radome wall from being subjected to forces exerted by the weight of the overhanging boom 50 and its associated parts, a counterbalancing weight bucket W is hung on the right hand end of the support 90 and is preferably filled with lead pellets so that a precise balance of weight is obtained on either side of the axis of the shaft 42 which serves as a fulcrum, thereby producing a state of equilibrium about this horizontal axis.

Other counterbalancing devices 181) are provided to offset the total weight of the vertically movable slide 26 and all of the elements supported thereby in order to facilitate the vertical displacement of this assembly at the relatively slow rate required.

The counterhalancing devices 11H? are of the constant tension type, sometimes referred to as negato-r springs, and are commercially available, and consist of spring ribbons 1112 tightly coiled within the devices 1%, uncoiling when the cross rail 26 moves downwardly and coiling when it moves upwardly, and exerting the same amount of force upon the cross rail in any position or with it moving in either direction. A cross plate 104 is supported on raised brackets 1(16 fixedly mounted on a cross memher 107 fixed at its ends to the tops of the vertical supporting members 18 and 20. The cross plate 104 in turn supports a predetermined number of counterbalancing devices 100, the number depending on the capacity of each device and the total weight to be balanced thereby.

Interconnecting the heads 30 and 32 and freely rotatable in a pair of bearing housings 1118 and 11d fixed to or integral with the heads 30 and 32 is a shaft 112. The outer end of each of the spring ribbons 102 is threaded around the underside of the shaft 112 and anchored by a screw 114 to the cross plate 1114. In this manner, the force exerted by the spring ribbons 1G2 counterbal-ancing the slide 26 and its associated parts is applied thereto through rotatable shaft 112.

A feed mechanism is provided for raising and lowering of the slide 26 on the vertical slideways 22 and 24. It comprises a pair of synchronously rotatable feed screws 116 and 118 journaled in the supporting members 18 and 20 respectively. At the upper ends of the screws 116 and 118 are fixed worm wheels 120 and 1 22 engaged by worms 124 and 126 fixed to and rotatable with a shaft 128 journaled in bearings not shown. Fixedly mounted to the shaft 128 is a sprocket 130 connected by chain 132 to d an idling sprocket 134 rotatable on a shaft 136 fixed to the supporting member 20.

The idling sprocket 134 has a sprocket 133 integral with or fixed to it. A chain 146* connects the sprocket 133 with another sprocket 142 keyed to a rotatable shaft 144. Integral with or fixed to the sprocket 1421s a sprocket 145 connected by a chain 148 to a sprocket 156 fixed to the output shaft 154 of a speed reducer 152. An input shaft 156 of the speed reducer has fixed to it a pulley or sheave 158 connected by a belt or belts 16% to a sheave 162 fixed to the rotatable shaft of a reversible motor M, mounted on a bracket 17d fixed to the base 19.

A gear train is provided for traversing the table 12 and a workpiece or radome R past the cutting tool or grinding wheel 96. The train consists of a gear 172 fixed to the rotatable shaft 144 journaled in bearings not shown in the base 1%. The gear 172 meshes with an idler gear 17% rotatable on a shaft 176 fixed to the base 10. A declutchable gear 178, fixedly mounted on a shaft 189 slidable and rotatable within bearings not shown in the base it), normally meshes with the gear 176 and a rack 182 fixed to the table 12.

The gear 173 is in constant mesh with the rack 13 2 but may be engaged or disengaged selectively from the gear 174 by moving the shaft 18% either inwardly or outwardly as required using the handle secured to the end of shaft 180. In the disengaged position of the gear 175, the table 12 and the vertical slide 26 may be traversed independently for procuring the correct initial relationship between them when the machine is set up. The table 12 is traversed manually by rotating the shaft and gear 178.

,With the gear 178 in engagement with the gear 174, a linear relationship is maintained between the horizontal movement of the table 12 and the vertical movement of the slide 26. Such a relationship is satisfactory for grinding a radome R having a lengthwise contour of constant curvature such as that illustrated in FIG. 1 provided that the constant ratio of the respective movements is such as to maintain the grinding wheel 96 and the coacting follower 8? in the desired orientation relative :to the surface being ground, that is with the grinding wheel 96 and the coacting follower 89 rotating in a common plane disposed substantially perpendicular to the portion of the surface being ground, as illustrated in FIG. 1.

It will be obvious that suitable modification of the means for synchronizing the horizontal movement of table 12 and the ventical movement of the slide 26 will be necessary to maintain the proper orientation of the grind ing Wheel 96 and the follower 89 relative to the surface being ground when that surface has a variable curvature lengthwise of the radome. For example, direct interconnection through suitably sized gears can be modified to include a linkage incorporating a cam and a follower with the cam surface contoured to correspond to variations in the curvature of the surface to be ground. One such arrangement is illustrated in FIG. 4 showing details of a drive train including a cam mounted on the supporting member 20 and a follower supported upon the linkage included in the drive train.

Apparatus is provided for properly supporting the radome or workpiece R in a predetermined position preferably so that the longitudinal chord of the arc of the radome wall is substantially parallel to the table 12 with the axis of rotation of the radome at an angle to the table 12. By supporting the radome in this manner the boom 50 and the cutting tool support 90 are disposed substantially parallel to the table 12, when the table is disposed so that the grinding wheel 96 and the follower 89 are midway between the ends of the arc, and the slide 26 is disposed midway of its full stroke, as shown in FIG. 1. Another advantage in the way the radome is mounted is that the angle that the boom 56 and the support 90 assume relative to the horizontal plane of table 12 is held to a minimum and this angle will be substantially the same when the grinding wheel is at either end of the radome R, at which time the slide 26 will be at either its uppermost or at its lowermost position.

The apparatus for supporting the workpiece comprises four adjustable work supports 200. The work supports 200 are identical and consist basically of the same elements; therefore, it is deemed unnecessary to describe all of them. Each of the work supports 209 has a base 202 upon which is slidably mounted a slide 294, adjustably positioned by a nut and screw mechanism 266. On the slide 294 is pivotally mounted a plate 208 adjustably fixed in position at the proper angle by bolt and nut arrangement 210. A pair of rollers 212 rotatable on a shaft 214 fixed to a bracket 216 is adjustably fixed on the plate 208 at the proper angle so that the rollers 212 which may have a tapered or convex shaped periphery will contact the underside of the radome. Also pivotally supported on each of the slides 204 in bearing blocks 218 is an elongated strip- 220 to which is adjustably fixed a roller support 222 with a roller 224 rotatably mounted thereon urged by a spring 226 to maintain contact with the radome above its axis of rotation and helping to constrain the radome and yet maintain the radome R freely rotatable Within the cradle arrangement formed by the rollers 212. Each of the work supports 26% are adjustably fixed to the table 12 by bolts 228 engaging T-slots in the table 12. A spacing block 239 is provided to properly position one pair of work supports 2% at a higher level.

A pair of end supports, one of which is shown, are provided to take the end thrust of the load produced due to the incline at which the radome R is maintained. These supports are identical and each comprises an adjustable L-shaped bracket 232 fixedly mounted on the table 12 by bolts engaging T-slots. A roller 234 is rotatably mounted at its upper end and contacts the circular end surface of radome R mainta ning the radome in the proper longi tudinal position without restricting the rotation thereof. Both of the rollers 234 contact the end surface of the radome diametrically opposite each other.

A radome or workpiece rotating mechanism is provided comprising a base 236 fixed by bolts in an adjusted position on the table 12. Pivotally mounted on the base 236 is an adjustable plate 238 locked in place by nut and bolt elements 240. Fixed to the plate 240 is a combined motor and gear reduction unit D for rotating the radome at a predetermined rate. This unit may conveniently comprise a suitable commercially available variable speed unit. The output shaft of the motor and gear reduction unit D is connected to a universal joint 242 provided with a threaded stud 244 at its right hand end upon which a member 246 is adjustably fixed which has a deformable frictional drive cup 248 integral therewith made of a resilient material contacting the spherical nose portion of the radome R. It can be seen that the axis of the output shaft of the motor and gear reduction unit D is located coincident with the axis of the radome by simply adjust ing the plate 236; and that the contact pressure between the spherical nose of the radome R and the drive cup 248 is obtained by adjusting the base 236 on the table 12.

Operation The operation of the machine will now be described. The radome or workpiece is first loaded in the machine and supported therein in the manner illustrated in the drawings and described above. With the table 12 in a left hand position and a table dog 250, adjustably fixed to the table 12, against a stop block 252, the roller 89 is positioned in contact with the workpiece near its extreme right hand end as shown at 89a in FIG. 1. The vertical slide 26 will be at its low or starting position with the boom 50 and the support 99 swung upwardly at a slight angle about the pivot shaft 42.

The motor and gear reduction unit is started, rotating the radome. Next the grinding wheel is caused to be rotated by admitting air to the pneumatic drive therefor. Then by rotating the handle 84, the slide 78 and the follower or roller 89 supported thereon is fed downwardly,

indirectly moving the grinding wheel or cutting tool 96 into engagement with the internal surface of the radome R to be ground or machined. The follower is then advanced an additional distance equal to the amount to be removed during one pass of the grinding wheel across the workpiece. Now the gear 178 is moved into engagement with the gear 176 by means mentioned above and then a switch 262 is closed so the table 12 will move toward the right as seen in FIG. 1. The usual start switch 264 is then closed, starting the reversible motor M rotating at a fixed speed and the synchronous movements of the slide 26 and the table 12 at predetermined greatly reduced rates, relative to that of motor M.

As the table 12 and radome R move to the right, the vertical slide moves upwardly and the boom 50 and the axis of the follower 89 gradually assumes a horizontal position from its original upward sloping position at about the mid point of the radome, as shown in FIG. 1, and the vertical slide 26 is disposed at the half way point of its total vertical travel. Beyond the mid point of the radome, the boom 50 starts to gradually slope downwardly as the pivot shaft 42 and the slide 26 continue to move upwardly. The radome and table 12 continue to move toward the right until the follower roller 89 and grinding wheel 96 reach the point of tangency between the radome wall and its spherical nose portion. At this point the table dog 250 is about to contact a stop block 254 adjustably fixed to the base 10 and the operator stops the motor by actuating a conventional stop switch 266 opening the circuit to the motor M, stopping the table 12 in the right hand position with the slide 26 in the upper position.

The operator now may or may not rotate the handle 84 at this time to feed the grinding wheel 96 for another cut, depending on whether he is getting a better finish by making a complete cycle in and out with the original setting.

A switch 263 is then closed to reverse the direction of rotation of the motor M; after which the start switch 264 is again closed starting the motor M rotating, moving the table 12 to the left and the slide 26 downwardly. As the finishing operation slowly continues, the boom 50 operates in a manner corresponding to that described during the upward movement of the slide 26, that is the boom Stl is first positioned sloping downwardly from slide 26 and then slowly assumes a horizontal position and finally is positioned sloping upwardly from slide 26 taking the position it was in at the beginning of the cycle.

When the follower roller reaches the position 89a and the table dog 25% is about to contact the stop block 252 again, the motor is again stopped by opening the stop switch 266. The grinding wheel 86 is then fed a predetermined amount to take another cut, the switch 262 is closed to preset the direction of rotation of the motor so that the table 12 will move to the right, and the starting switch 264 is closed recycling the operation to grind the workpiece or radome in the same manner as above disclosed until the desired uniform wall thickness and finish is obtained.

The electrical circuit for controlling reversible motor M illustrated in FIG. 5 will function as described above with selector switch SS1 positioned as shown in FIG. 5.

If it is desired, well known means may be employed by which the table 12 and vertical slide 26 can be automatically stopped, reversed and started again such as having the dog 25% operate limit switches controlling the reversing switch.

It will be evident from the showing in FIG. 5 that the reversible motor M will be controlled by the limit switches LS1 and LS2 when the selector switch SS1 is moved to the right as seen in FIG. 5 from the position shown in FIG. 5.

Since various starting, stopping and reversing switches are commercially available, and since the specific details of these switches form no part of the instant invention, the details of these switches and of the circuits interconnecting these switches and the motor M have been omitted from this description.

From the description above, it is apparent that there has been provided by this invention a simple, well balanced, and practical apparatus for accurately grinding the internal surface of a radome or the like without subjecting the wall of a workpiece to injurious loads, of which many modifications may be made by those skilled in the art without departing from the spirit or scope of this invention, as defined in the accompanying claims.

What is claimed is:

1. Apparatus for machining the internal surface of a hollow thin walled elongate workpiece symmetrical about a central axis and having a longitudinally curved external surface, comprising means for supporting such a workpiece with its central axis in a fixed predetermined attitude, means for rotating such a workpiece about its central axis, a supporting pivot movable transversely relative to an elongate workpiece supported upon said means for supporting a workpiece, a supporting member pivotally mounted upon said supporting pivot including first and second elongate portions projecting therefrom, a cutter means mounted at the outer extremity of the first said portion, a follower means mounted at the outer extremity of the second said portion spaced from and in opposed relation to said cutter means, a drive means operable to produce relative longitudinal move ment between a workpiece and said cutter means and coordinated relative transverse movement between a workpiece and said supporting pivot for said pivotally mounted supporting member, whereby the internal surface of a workpiece may be finished by said cutter means to provide a workpiece wall of uniform predetermined thickness.

2. Apparatus for machining the internal surface of a hollow thin walled elongate workpiece symmetrical about a central axis and having a longitudinally curved external surface, comprising a slidably movable first support, means for supporting such a workpiece on said first support with its central axis in a fixed predetermined attitude, means for rotating such a workpiece about its central axis, a slidably movable second support, a supporting member pivotally mounted upon said second support including first and second elongate portions projecting therefrom, a cutter means mounted at the outer extremity of the first said portion, a follower means mounted at the outer extremity of the second said portion spaced a predetermined distance from and in opposed relation to said cutter means, a drive means operable upon said first support and said second support to produce relative longitudinal movement between a workpiece and said cutter means and coordinated relative transverse movement between a workpiece and said second support on which said supporting member is pivotally mounted, whereby the curved internal surface of a workpiece may be finished by said cutter means to provide a workpiece wall of uniform predetermined thickness.

3. A device as described in claim 2, and, in addition, means for adjusting the position of said follower means to vary the space between said follower means and said cutter means.

4. Apparatus for grinding the internal surface of a hollow thin walled elongate workpiece symmetrical about a central axis and having a longitudinally curved smoothly finished external surface, comprising a first support slidably mounted for horizontal displacement, means for supporting such a workpiece on said first support with its central axis in a fixed predetermined attitude, means for rotating such a workpiece about its central axis, a second support slidably mounted for vertical displacement, at supporting member pivotally mounted upon said second support including first and second spaced generally paral lel elongate portions projecting therefrom, a grinding wheel rotatably mounted transversely of and at the outer extremity of the first said portion, means operable to rotate said grinding wheel, a flat rotary follower means mounted transversely of and at the outer extremity of the second said portion spaced from and in opposed coplanar relation to said grinding wheel, a drive means operable upon said first support and said second support to produce relative longitudinal movement between a workpiece and said grinding wheel and coordinated relative transverse movement between a workpiece and said second support on which said supporting member is pivotally mounted, whereby the internal surface of a workpiece may be finished by said grinding wheel to provide a workpiece wall of uniform predetermined thickness, said drive means including means effective continuously to coordinate the relative rates of movement of said first sup port means and said second support means so that the common plane in which said grinding wheel and said follower means rotate is maintained substantially per pendicular to the portion of a workpiece engaged by the grinding wheel.

5. A device as described in claim 4, and, in addition, a counterweight attached to said pivotally mounted supporting member adjustable to balance said supporting member precisely about its pivot, and a counterbalance means continuously effective to counterbalance the weight of both said second support and the supporting member pivotally mounted thereon as said second support is displaced vertically.

6. Apparatus for machining the internal surface of a hollow thin walled elongate workpiece symmetrical about a central axis and having a finished external surface so as to produce a workpiece wall of uniform predetermined thickness, comprising slidably movable first support means for supporting such a workpiece with its central axis in a fixed predetermined attitude, means for rotating such a workpiece about its central axis, second support means mounted for movement transversely of a workpiece supported by said first support means, a supporting member pivotally mounted upon said second support means first and second spaced generally parallel elongated portions projecting from said pivotally mounted supporting member, cutter driving means mounted adjacent the end of said first elongate portion, cutter means mounted upon said cutter driving means and rotated about a first axis of rotation thereby, follower means rotatably mounted on said second elongate portion for rotation about a second axis of rotation spaced from and substantially parallel to the axis of rotation of the cutter means, and drive means operable to produce longitudinal movement of said first support means and a workpiece supported thereon relative to said second support means and concurrent coordinated transverse movement of said second support means and the supporting member mounted thereon relative to said first support means and a workpiece supported there- 7. Apparatus for machining the internal surface of a hollow thin walled elongate workpiece symmetrical about a central axis and having a finished external surface so as to produce a workpiece wall of uniform predetermined thickness, comprising an elongated base, first support means slidable lengthwise of said base for supporting such a workpiece with its central axis in a fixed predetermined attitude, means for rotating such a workpiece about its central axis, second support means slidable transversely of said base, a supporting member pivotally mounted upon said second support means, for movement with said second support means transversely of a workpiece supported by said first support means, first and second spaced generally parallel elongated portions projecting from said pivotally mounted supporting member, cutter driving means mounted adjacent the end of said first elongate portion, cutter means mounted upon said cutter driving means and rotated about a first axis of rotation thereby, follower means disposed in alignment with said cutter means rotatably mounted on said second elongate portion for rotation about a second axis of rotation spaced from and substantially parallel to the axis of rotation of the cutter means so as to provide a space between said cutter means and said follower means equal to the desired thickness of the workpiece wall, and drive means operable to produce longitudinal movement of said first support means and a workpiece supported thereon relative to said second support means and concurrent coordinated transverse movement of said second support means relative to said first support means and a workpiece supported thereon.

8. A device as described in claim 7, and, in addition, means for adjusting the position of said follower means transversely relative to said second elongate portion to vary the space between said follower means and said cutter means.

9. Apparatus for machining the internal surface of a hollow thin walled elongated workpiece symmetrical about a central axis and having a finished external surface so as to produce a workpiece wall of uniform predetermined thickness, comprising a base assembly including a bed portion with elongated horizontal Ways on its upper surface and a column portion provided with vertical Ways, first support means for supporting such a workpiece with its central axis in a fixed predetermined attitude, said first support means being mounted for sliding movement lengthwise of the horizontal ways, means for rotating such a workpiece about its central axis, second support means mounted for movement transversely of a workpiece supported by said first support means, said second support means being mounted for sliding movement along the vertical ways, a supporting member pivotally mounted upon said second support means, first and second spaced generally parallel elongated portions projecting from said pivotally mounted supporting member, cutter driving means mounted adjacent the end of said first elongate portion, fiat circular cutter means mounted upon said cutter driving means and rotated about a first axis of rotation thereby for engagement with the inner surface of a workpiece, a fiat circular follower means rotatably mounted on said second elongate portion coplanar with said cutter means for rotation about a second axis of rotation spaced from and substantially parallel to the axis of rotation of the cutter means for engagement with the outer surface of a workpiece, and drive means operable to produce longitudinal movement in a predetermined direction of said first support means and a workpiece supported thereon relative to said second support means and concurrent coordinated transverse movement in a predetermined direction of said second support means relative to said first support means and a workpiece supported thereon, said drive means including coupling means effective continuously to maintain respective rates of movement of said first support means and said second support means coordinated so that the common plane in which said cutter means and said follower means rotate is maintained substantially perpendicular to the portion of the workpiece engaged by the cutter means.

10. A device as described in claim 9, and, in addition, a counterweight attached to said pivotally mounted supporting member adjustable to balance said supporting member precisely about its pivot, and a counterbalance means mounted upon said base assembly continuously effective to counterbalance the weight of both said second support means and the supporting member pivotally mounted thereon as said second support means is moved along the vertical ways.

References Cited in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR MACHINING THE INTERNAL SURFACE OF A HOLLOW THIN WALLED ELONGATE WORKPIECE SYMMETRICAL ABOUT A CENTRAL AXIS AND HAVING A LONGITUDINALLY CURVED EXTERNAL SURFACE, COMPRISING MEANS FOR SUPPORTING SUCH A WORKPIECE WITH ITS CENTRAL AXIS IN A FIXED PREDETERMINED ATTITUDE, MEANS FOR ROTATING SUCH A WORKPIECE ABOUT ITS CENTRAL AXIS, A SUPPORTING PIVOT MOVABLE TRANSVERSELY RELATIVE TO AN ELONGATE WORKPIECE SUPPORTED UPON SAID MEANS FOR SUPPORTING A WORKPIECE, A SUPPORTING MEMBER PIVOTALLY MOUNTED UPON SAID SUPPORTING PIVOT INCLUDING FIRST AND SECOND ELONGATE PORTIONS PROJECTING THEREFROM, A CUTTER MEANS MOUNTED AT THE OUTER EXTREMITY OF THE FIRST SAID PORTION, A FOLLOWER MEANS MOUNTED AT THE OUTER EXTREMITY OF THE SECOND SAID PORTION SPACED FROM 